Surface type burner control



March 13, 1956 Filed June 11, 1952 2 Sheets-Sheet 1 gwvwwtw Hf/V/PYLfFUYMUH/V r El Q- E- 334, (a

March 13, 1956 H. L. MOHN SURFACE TYPE BURNER CONTROL 2 Sheets-Sheet 2 Filed June 11, 1952 PIP/MARY C'O/V T/POL BURNER SWITCH 27 5E E l/E/V/P) Af/POY MOl/A/ United States Patent 2,738,132 SURFACE TYPE BURNER CONTROL Henry Leroy Mohn, York, Pa., assignor to York-Shipley, Inc., York, Pa., a corporation of Delaware Application June 11, 1952, Serial No. 292,836 4 Claims. (Cl. 236-9) This invention relates to hot water heating systems and more particularly to improvements in a control unit and system for a house heating boiler containing a taukless coil for heating domestic hot water.

Heating systems in which a coil for heating water for domestic uses is immersed in the hot water of a house heating unit are well known. Such a system is shown and described in my Patent 2,540,055, dated January 30, 1951. In systems wherein the domestic hot water coil is not connected to a separate hot water storage tank, it is necessary that the tankless coil be of sufficient size and be immersed in water of sufficiently high temperature to heat a normal flow of water from the water main to a temperature adequate for domestic uses.

It is therefore an object of this invention to provide a novel control system for improving the operation of heating systems having a tankless coil in a heating boiler.

It is a further object of this invention to provide a control system responsive to both the temperature of the water supply and the temperature of the heating boiler to control operation of the boiler heating means.

It is another object of this invention to provide a novel control unit associated with a tankless water heating coil.

It is a still further object of this invention to provide a system for starting a burner mechanism quickly upon flow of cold water into a tankless heating coil.

Other objects and advantages of this invention will be readily apparent from the following description and the accompanying drawings illustrating a preferred embodiment of the invention.

In the drawings,

Figure l is a diagrammatic elevational view of a house heating boiler having a tankless coil and control unit applied thereto.

Figure 2 is a side elevational view of the tankless coil, control unit, and mounting plate removed from the heating boiler of Figure 1. a

Figure 3 is an end elevational view of the control unit shown in Figure 2.

Figure 4 is a front elevational view, partly cut away, of the control unit.

Figure 5 is a plan view of the control unit.

Figure 6 is a diagrammatic wiring diagram of the control system.

Referring to the drawings, Figure 1, a house heating boiler is designated by the numeral 10. The boiler 10 may be of any conventional type for heating hot water for house heating purposes. The boiler 10 may be fired by a gas burner or by an oil burner 11. A flue connection is indicated by the numeral 12. A suitable hot water outlet 13 and a return connection 14 are provided for connection to a housing heating system, a motor-driven circulator 15 being provided between the return connection 14 and the boiler 10. An orifice nipple connection 16 may be provided betweenthe return connection 14 and the upper portion of the boiler. The boiler 10 may be provided with the usual pressure and temperature indicator gauge 17 and with the customary casing, insulation, and other connections, not shown.

A tankless coil 20 for heating Water for domestic uses is inserted in the upper part of the boiler 10 where it is immersed in the boiler water. The coil 20 is supported by a control fitting 21 and a plate 22 attached to the side of the upper portion of the boiler 10. The plate 22 2,738,132 Patented Mar. 13, 1956 ICC is provided with an outlet connection 23 extending through the plate. The control fitting 21 is provided with a domestic water inlet connection 24 extending through the plate 22, and is provided with a connection 34 for the coil 20.

The control system includes, as shown in Figure 1, a conventional room or house thermostat 25, a primary burner control 26 mounted on the boiler 10 adjacent to or in the flue 12, and a pair of snap-acting thermostats 27 and 28 mounted on the plate 22, and connections between the thermostats, circulator motor 15, burner motor 11 and the power line 29. The primary burner control 26 may be a conventional safety device which is responsive to temperatures in the flue area, and serves to cut-off the burner 11 if the flue temperature does not rise a predetermined number of degrees in a predetermined number of seconds after the burner is energized. The safety control 26 therefore stops operation of the burner 11 when misfiring occurs in starting the burner, and is also effective to cut'oif the burner when misfiring occurs during operation of the burner and when flue temperatures exceed a predetermined safe limit. The wiring circuit for these devices is shown in detail in Figure 6 and will be described hereinafter.

Referring to Figures 3, 4, and 5, the control fitting 21 is formed of metal and is provided with two parallel passageways 31 and 32. The passageway 31 communicates with the inlet 24 at one end of the fitting. Near the other end of fitting 21 a lateral passage 33 connects passageway 31 with passageway 32. The end of passageway 32 adjacent to the inlet 24 is in communication with the outlet 34. The inlet end of the coil 20 is insorted in the outlet 34 and secured to the fitting 21 by soldering, brazing or the like. The fitting 21 may be provided with plugs 35 brazed thereto to close the openings made in forming the passageways 31 and 32 and passage 33. The control fitting 21 therefore provides that water entering the inlet 24 flows through the passageway 31, then through passage 33, and then through passageway 32 to the connection 34 and into the coil 20.

The control fitting 21 is mounted on the boiler water side of plate 22 with the inlet connection 24 extending through the plate 22. The fitting 21 may be of brass and the plate 22 of steel. The fitting 21 is mounted with its face 36 in contact with the inner surface of plate 22 and is secured thereto by brazing around the inlet 24 and by several brazed tacks along the edge of the fitting to secure the fitting against the plate 22 in good heat conducting contact.

The thermostats 27 and 28 are mounted on the outer surface of plate 22 with thermostat 28 adjacent to the passage 33 of the fitting 21, as shown in Figure 1. The thermostat 27 is mounted spaced from the thermostat 28 and spaced from the fitting 21 so that its responds primarily to the temperature of the water in boiler 10. Thermostat 28 responds primarily to the temperature of water in the passageways 31, 32, and 33 of fitting 21. The thermostats 27 and 28 are preferably of the conventional bimetallic disc type which operate with a snap action. The thermostat discs thereof may be mounted substantially parallel to the plate 22 and may be spaced one sixteenth to one-eighth of an inch from the plate.

As illustrated diagrammatically in Figure 6, the thermostat 27 may be of the off-on type which closes a switch contact when the temperature drops to a predetermined value, and snaps open when the water temperature rises to another predetermined value. The thermostat 28 is of the double-throw type, and snaps to close contacts when the temperature drops to a predetermined value, and snaps to close on a different contact when the temperature rises to a predetermined value. The house thermostat25 is of any conventional type and closes a circuit when room temperature drops and the thermostat calls for more house heat. The primary burner control 26 is, as mentioned above, of any conventional type that opens the burner circuit when the flue temperature fails to rise or drops rapidly, to act as a safety control. One side of the power supply line 29 is connected to the motor of circulator 1.5, to the control 26 and to the motor of burner 11. The other side of line 29 is connected through the thermostat 25 to the thermostats 27 and 28. The thermostat 27 is connected through the primary burner control 26 to the burner 11. The thermostat 28 is connected to short out the room thermostat 25 when it snaps to the cold position, and is connected to the motor of circulator 15 in the hot position.

The operation of the control system will now be de scribed. The system is at rest when the water in boiler is at a predetermined desired temperature and the house thermostat 25 is not calling for the circulation of house heating water. In this hot boiler condition, boiler thermostat 27 is in the open circuit hot position, house thermostat 25 is in the open circuit position, thermostat 28 is in the hot position, and the burner 11 and circulator 15 are not operating. When the house thermostat 25 calls for house heat, it closes and thereby immediately starts operation of the circulator 15 and starts the burner 11. It the burner 11 fails to fire properly, the primary safety control 26 operates to cut otf the burner 11 when the flue temperature has not risen to a predetermined value in about sixty seconds after burner operation was initiated. When the burner operation causes the water in boiler It) to reach the predetermined desired temperature, boiler thermostat 27 opens to cut off the burner 11. When house thermostat 25 no longer calls for heat, it opens and cuts off operation of the circulator 15. Regardless of the condition of the house heating control system described above, withdrawal at any time of domestic hot water from the coil in boiler 10 causes relatively colder water from the conventional water supply to flow into the coil 20 through passages 31, 33, and 32, of fitting 21, thereby causing thermostat 28 to move to the cold position and start operation of the burner 11. It is found that the construction illustrated and described guarantees quick burner response to demands for domestic hot water. The flow of cold water directly adjacent the thermostat Z8 is effective to initiate burner operation as quickly as ten seconds after domestic hot water is drawn. This is important where tankless domestic water heating coils are installed in boiler units or" relatively small capacity. Every second that can be saved between the start of the hot water draw and the operation of the burner 11 means better domestic hot water performance. When the draw of domestic hot Water causes the water supply to operate the thermostat 2 a to the cold position, such action immediately cuts off operation of the circulator 15 if it happens that the circulator is then operating to supply house heating. The control system therefore gives priority to demands for domestic hot water by interrupting the circulation of house heating water. Since the demands for domestic hot water are intermittent and usually of relatively short duration. it is found that the resulting temporary interruption to forced circulation of house heating water to the house does not have any undesirable effect on the general maintenance of desired house temperatures. The system is simple and fast acting, and eliminates the need for a domestic hot water storage-tank in normal house installations. It is to be understood that the novel control system described has been illustrated somewhat diagrammatically for the purposes of simplicity, and that suitable relays and low voltage supply may be used for operation of the several thermostats at lower than line voltages.

It will also be understood and apparent that many changes in minor details, proportions, and design may be carried out within the scope of this invention as defined in-the following claims.

What I claim is:

1. A system for heating and circulating water for space heaters and for heating water for domestic use comprising in combination, a water chamber for containing space heating water, a domestic water heating coil immersed in the upper portion of said water chamber, a burner for heating water in said water chamber, a circulator for circulating space heating water to and from said chamber, said domestic hot water heating coil having an inlet and an outlet, a double-throw thermostatic switch mounted adjacent to said coil inlet and responsive to the temperature of water in said coil inlet, said switch being electrically connected to said circulator and to said burner to de-energize said circulator and to energize said burner when the temperature of water in said coil inlet drops to a predetermined value.

2. A system for heating and circulating water for space heaters and for heating water for domestic use, comprising in combination, a boiler for containing space heating water, a domestic water heating coil immersed in the upper portion of said water boiler, a burner for heating water in said boiler, a circulator for circulating space heating water to and from said boiler, said domestic hot water heating coil having an inlet and an outlet, a double-throw snap-acting thermostatic switch mounted adjacent to said coil inlet and responsive to the temperature of water in said coil inlet, a second thermostatic switch mounted on said boiler and responsive to the temperature of water in said boiler, and a third thermostatic switch remote from said boiler and responsive to the temperature of the space to be heated, said third switch being electrically connected through said doublethrow switch to said circulator, and said double-throw switch being electrically connected through said second switch to said burner.

3. A control assembly for mounting a tankless domestic water heating coil in the upper portion of a boiler, said assembly comprising, in combination, a closure plate to be secured to and form a part of the upper portion of a boiler, a fitting in engagement with the inner side of said plate and having an inlet connection extending outwardly through said plate, said fitting having a lateral passageway communicating with said inlet and located adjacent to the inner side of said plate, said fitting also having an outlet communicating with said lateral passageway for connection to said heating coil, said plate having an outlet connection extending therethrough for said heating coil, and a double-throw thermostatic control switch mounted against the outer wall of said plate adjacent to said lateral passageway of said fitting and responsive to the temperature of water in said fitting passageway.

4. A control assembly for use in mounting a tankless domestic water heating coil in a Water boiler, said assembly comprising a plate, a fitting secured to said plate, an inlet connection extending from said fitting outward through said plate, said fitting defining a lateral passageway adjacent to the inner surface of said plate for connecting said inlet to a water heating coil, a double-throw snap-acting thermostatic switch secured on the outer surface of said plate adjacent to said passageway, and a second thermostatic switch secured to the outer surface of said plate remote from said fitting.

References Cited in the file of this patent UNITED STATES PATENTS 2,073,676 Broderick Mar. 16, 1937 2,248,304 Mueller July 8, 1941 2,257,442 Yula Sept. 30, 1941 2,273,375 Ray Feb. 17, 1942 2,312,353 Miller Mar. 2, 1943 2,340,844 Dillman Feb. 1, 1944 2,540,055 Mohn Jan. 30, 1951 

